A liquid delivery device is a device that supplies a necessary liquid solution using a pump or others to a chemical analysis apparatus in which samples are reacted and analyzed. For example, Japanese Patent Application Laid-Open Publication No. 2005-274148 (Patent Document 1) relates to a liquid delivery device for liquid chromatography, and describes a gradient device including first flow passage, a second flow passage, a third flow passage, which each extend in predetermined directions, fourth flow passages that are n flow passages and that are connected to a Id thinner than the first flow passage, fifth flow passages that are n flow passages and that are connected to and thinner than the second flow passage, and a mixture vessel for gradient liquid (solvent) delivery for supplying gradient eluent to an analytical column while gradually changing a composition of the gradient eluent.